1. Technical Field
The present invention relates to a user-manipulated, force resisting exercise device for exercising the legs. In particular, the invention relates to a leg exercise device which has an adjustable knee support to provide proper positioning of the leg and accommodate users of various sizes.
2. Background Art
Various types of leg exercising devices are well-known in the art. In an arrangement which is typical, a leg lift device is used in conjunction with a bench or chair. The user sits on the bench with his or her legs hanging straight down. One or both of the user's ankles are hooked around a padded crossbar of a pivotable, weighted lever arm assembly connected to the bench. By applying pressure to the crossbar and straightening his or her legs, the user exercises the quadricep muscles, the large muscles of the front of the thigh. It is also common to equip these exercise devices with a second padded crossbar which allows the user to lie on the bench and engage the second crossbar with the back of the user's ankles. By bending the knee joint and applying a force against the crossbar, the user can rotate the pivotable, weighted exercise device. This exercises the hamstring muscles, the large muscles on the back of the thigh.
When exercising the quadricep muscles, however, many prior art devices have not taken into account the need to provide a device which accommodates users of various sizes. In order to perform a leg lift exercise for the quadriceps safely and obtain maximum benefit, it is essential that the user's knee be supported by a support underneath the knee and that the user's foot engage the exercise device at or near the ankle joint. This ensures that the maximum moment arm--the distance between the knee and contact with the weighted resistance--is used.
Some prior art devices have permitted the user to adjust a leg lift device to a comfortable position. For example, in my prior patent, U.S. Pat. No. 4,316,609, an adjustable leg lift device is shown. However, in this device the distance between the knee support crossbar and the ankle engaging crossbar is fixed. The device can be adjusted only to elevate the knee but not to adjust the moment arm between the knee and ankle. Thus, users with very short or very long legs must use the exercise device in a way which will not provide the maximum benefit of the exercise and may place an undue strain on certain muscles, bones, or joints.
Other adjustable leg exercise devices are also known. For example, U.S. Pat. No. 4,256,302 discloses a leg lift device mounted on a chair. The device is adjustable by raising or lowering the ankle engaging portion of the leg lift device. However, the device does not provide an adjustable knee support. U.S. Pat. No. 3,850,430 discloses an adjustable leg exercise device intended to be used on the floor. In this device the weight pivot arm is pivoted to the knee support. The device does not allow the support for the knee to be independently adjusted relative to the position of the ankle.